BirdAnalyst
Species · BCR 33 · BBS 2026 Release · 1966–2025

Bell's Sparrow In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsArid-land birds

Bell's Sparrow in Sonoran and Mojave Deserts has increased: up 44% on the route-weighted index since 1972.

+44%Since 1972TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
16Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Bell's Sparrow in Sonoran and Mojave Deserts. See the full index history below.

Bell's Sparrow In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, Bell's Sparrow in Sonoran and Mojave Deserts is projected to stay roughly flat through 2030, near 1.2 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±959.1%, with 100% of held-out values landing inside the 95% band.

+1%Change by 2030TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
1.2Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–2.495% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±959.1%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Bell's Sparrow in Sonoran and Mojave Deserts is projected to stay roughly flat through 2030, near 1.2 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±959.1%, with 100% of held-out values landing inside the 95% band.19692030
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20261.10.002.4
20271.10.002.4
20281.10.002.4
20291.10.002.4
20301.20.002.4

Routes In Sonoran and Mojave Deserts

Routes recording Bell's Sparrow in Sonoran and Mojave Deserts.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Willow Springs 2CALIFORNIA192025
Calif CityCALIFORNIA122015
GoldstoneCALIFORNIA102009
Kelso ValleyCALIFORNIA72025
OnyxCALIFORNIA52015
PearblossomCALIFORNIA52025
Ash MeadowsNEVADA42015
BarstowCALIFORNIA31998
Ft IrwinCALIFORNIA31981
Willow SpgsCALIFORNIA21981
InyokernCALIFORNIA22024
Lane MtnCALIFORNIA21973
Joshua TreeCALIFORNIA21981
LenwoodCALIFORNIA12012
Lucerne ValCALIFORNIA12025
Lone PineCALIFORNIA12024

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.